Aestrophysics and Cosmology

Question 1

Universe

Answer 1

Large collection of billions of galaxies

Question 2

Galaxy

Answer 2

Large collection of billions of stars

Question 3

Comet

Answer 3

• Very elliptical
• orbits sun

Question 4

Planet

Answer 4

• circular
• orbits sun

Question 5

Moon

Answer 5

• circular
• orbits planet/earth

Question 6

WHy is Gravitational field strength different on the moon?

Answer 6

• lower on the moon
• the moon has a lower mass than Earth

Question 7

Evolution of a Star - higher mass than sun

Answer 7

• nebula
• protostar
• main sequence
• red supergiant
• supernova
• black hole or neutron star

Question 8

Evolution of Star - same mass/lower mass than sun

Answer 8

• neubla
• protostar
• main sequence
• red giant
• white dwarf

Question 9

Evolution of star

Answer 9

1. Nebula is a cloud of gas and dust
2. Gravity pulls particles together to form a protostar
3. gravity squeeze particles closer together creating a more dense star
4. This raises the temperature and pressure
5. Hydrogen nuclei fuse to form helium nuclei which releases energy
6. Enters main seqeunce phase - stable period of star
7. Outward pressure from nucleur fusion = inward pressure from gravity
8. Hydrogen runs out = no more fusion
9. Outward pressure is removed, inward pressure contracts the star into a small ball
10. Becomes hot and dense - more nuclear fusion = star expands
11. Either a red giant or red super giant

Question 10

Small Star

Answer 10

1. Becomes unstable
2. sheds outer layer
3. leaving a hot dense solid core called a white dwarf
4. overtime it cools and becomes darker which forms a black dwarf
5. It no longer has enough energy to emit light

Question 11

Large Star

Answer 11

1. more nucleur fusion - expanding and contracting
2. eventually explodes creating a supernova
3. condenses into a dense core called a neutron star
4. very dense then it collapses into a balck hole

Question 12

Absolute Magnitude

Answer 12

The measure of brightness of a star at a standard distance

Question 13

HR Diagram

Answer 13

x-axis = colour (blue to red)
y-axis = absolute magnitude (smallest to largest)

Question 14

The Big Bang Theory

Answer 14

Space was dense and hot
Single point exploded
Space continues to expand

Question 15

Red-Shift

Answer 15

When object moves away from earth the wavelength increases

Question 16

Red Shift is evidence for the Big Bang Theory

Answer 16

• Galaxies are mobing away from earth
• greater red shift = increase wavelength = further from earth
• more distant galaxies move faster
• the universe is expanding

Question 17

CMBR is evidence for the big bang theory

Answer 17

• low frequency microwave radiation detected - coming from all directions
• shows the universe is expanding and cooling
• universe expands = background Radiation drops in frequency
• CMBR is evenly spread
• CMBR is the remains of energy released from the Big Bang

Question 18

Evidence for the Big Bang

Answer 18

1. Red Shift
2. Cosmic Microwave Background Radiation